The present invention relates to a terminal to be attached to a circuit assembly comprising an insulating substrate on which a circuit is printed and it relates to a terminal attachment structure which makes it possible to attach the terminal to the circuit assembly.
Japanese Utility Model Publication (kokai) No. 4-6172 discloses one example of the conventional lead terminal attached to a substrate in order to connect a circuit on the substrate with a lead. The lead terminal has a columnar pin part formed on one side thereof, a lead terminal part formed on the other side and a fit part arranged between the pin part and the lead terminal part. The lead terminal part is provided with a V-shaped groove defined by opposing pointed edges. In fitting, by inserting a lead into the groove under pressure, an insulating cover of the lead is peeled by the pointed edges. In this state, since a core part of the lead comes into electrical contact with the pointed edges, a distal end of the lead can be connected with the lead terminal electrically.
In order to fix the so-constructed lead terminal on the substrate, the pin part of the lead terminal is firstly inserted into an attachment hole formed in the substrate, so that the fit part abuts on a periphery of the attachment hole. Thereafter, the pin part projecting from the back surface of the substrate is soldered with a circuit on the substrate. In this way, the attachment of the conventional lead terminal to the substrate can be completed.
Thus, in the conventional lead terminal, the above insertion of the lead into the V-shaped groove facilitates the electrical connection of the lead with the circuit in the substrate.
Beside the above-mentioned terminal structure, there is also known another terminal structure which can be attached to the substrate by means except soldering. This terminal structure is provided by bending an elongated conductive metal plates. The terminal structure comprises a circuit-contact part which is to be fitted to the insulating substrate so as to expose itself on one side of the insulating substrate and a connecting part which penetrates through the substrate and projects on another side thereof. The insulating substrate is provided, on the former side, with a circuit printed thereon and electrically connected with the terminal structure. In assembly, by connecting the connecting part of the terminal structure with a mating terminal, the circuit on the insulating substrate can be connected with the mating terminal.
Now, providing that the lead is inserted into the above-mentioned lead terminal on pressure in the former case or that the terminal structure is connected with the mating terminal in the latter case, any force for the substrate will be applied on the lead terminal or the terminal structure. Consequently, the pin part soldered with the substrate may become rickety in the former case, while the circuit-contact part may be lifted from the insulating substrate thereby to cause the terminal structure to be clattered in the latter case.
In the former case, even if the lead terminal totters against the substrate in this way, no problem would be caused because the lead has only to be fitted into the V-shaped groove. To the contrary, if the circuit-contact part of the latter terminal is raised from the insulating substrate unsteadily, it would be caused a problem that cracks are produced in the circuit formed on the circuit-contact part, so that the circuit is broken down.